Powering your camera for long periods.

There have been a number of threads related to this subject over the last few months, each of which takes a subtly different view of the problem. User bwh13 suggested in a personal message that we bring the best of these ideas together in one place, so that is the purpose of this thread.

I would suggest that it might also be worth a Wikia page or two on best practice when hacking together a power source.I intend to add a few links here, back to previous posts on the subject, and if anyone else has any good ideas, this would be the place to share them, so fire me a PM if you want a link added here.

EDIT: In one of those meaningless coincidences of life, while I was writing the above, I spotted this on one of my favourite sites, I haven't had time to read it all yet, but since it is related I thought it worth a link to it.

I saved one of them to use when I have A/C power. I cut off the cable to the dummy battery on the other one, and spliced it to a 4mm barrel connector cable that plugs into the external battery above.

You don't need a voltage regulator with this setup. 8.4 volts powers both cameras fine.

The battery doesn't have a low voltage cutoff, which is an advantage, I think. The battery voltage should gradually go below the Canon low cutoff voltage, triggering an orderly, low voltage shut down. A sudden loss of external power in continuous mode leads to a loss of pictures, I discovered much to my dismay.

All of the current Canon DSLRs that I know of use a 2-cell Li-Ion pack.Supplying them with an external pack is thus very easy.Please beware of the dangers of Li-Ion batteries! Never use cheap cells. Use protection circuits.

Of course, Canon P&S cameras use a variety of battery types & voltages. But your cautionary note about Li-Ion cells is a good one.